Refrigerating apparatus



Dec. 29, 1936.

R. K. MILLER REFRIGERATING APPARATUS Filed March 26, 1934 2 Sheets-Sheetl Dec. 29, 1936. R. K. MILLER REFRIGERATING APPARATUS Filed March 26,1954 2 Sheets-Sheet 2 Patented Dec. 29, 1936 UNITED STATES"REFRIGERATING APPARATUS Ralph K. Miller, Dayton, Ohio, assignor to Gen-'eral Motors Corporation, Dayton, Ohio, a .cor-

poration of Delaware Application March 26, 1934, Serial No. 717,377

3 Claims. (Cl. 62116) This invention relates. to refrigerating apparatusand more particularly to two temperature refrigerators having separatecompartments for freezing and food storage.

At present practically all refrigerators manufactured have a singlecooling unit having all of its cooling surfaces at substantially thesame temperature for freezing purposes for the dual function of freezingwater and comestibles as well as cooling the air or atmosphere withinthe food compartment. This scheme has the objection that it unduly driesthe food com-' partment air and causes frost to collect upon thesurfaces of the evaporator. Practically the only exceptions are thosemanufacturers which employ a serially arranged expansion coil having thefirst portion of the coil for freezing and the remaining portions forcooling the food compartment. In such a system, however, there isdifficulty as to the control of the different temperatures throughoutthe portion of the coil within the food compartment.

It is an object of my invention to provide an improved two temperaturerefrigerator wherein relatively high evaporating pressures andtemperatures are maintained throughout the evaporating portion for thefood compartment and considerably lower evaporating pressures andtemperatures are'maintained throughout another portion of theevaporating means for freezing purposes.

It is another object of my invention to provide an improved controlsystem for two temperature refrigerators.

Further objects and advantages of the pres-' ent invention will beapparent from the following description, reference being had to theaccompanying drawings, wherein a preferred form of the present inventionis clearly shown.

In the drawings:

Fig. 1 is a vertical sectional view through a two temperaturerefrigerator embodying my invention;

Fig. 2 is a sectional view along the line 2-2 of Fig. 1;

Fig. 3 is a sectional view through one of the weight type of restrictionvalves shown in Figs. 1 and 2; and

Fig. 4 is a modified form of my improved two temperature refrigeratingsystem.

Referring to the drawings and more particularly to Fig: 1, there isshown a two temperature refrigerator including a cabinet 20, a food orhigh temperature compartment 2| within the middle portion of the cabinetand the separate freezing compartment 22 located directly above the foodcompartment 2| but'insulated therefrom. The food compartment 2| and thefreezing compartment 22 are enclosed by sheet metal inner walls 23 and24. Between the top sheet 5 metal wall of the food compartment and thebottom sheet metal wall of the freezing compartment, there is providedinsulating means 25 for preventing transfer of heat from the high tem-'perature food compartment 2| to the freezing 10 compartment 22.Insulating means 26 surrounds both the inner walls of the foodcompartment 2| and the freezing compartment 22.

Surrounding the insulating means 26 are the outer sheet metal walls 21.Separate doors and 15 door openings are provided for the foodcompartment 2| and the freezing compartment 22, the door for the foodcompartment being shown in Fig. 2 and designated by the referencecharacter 28. If desired, however, a single door may be used togetherwith some suitable means for sealing and insulating one compartment fromthe other.

Directly beneath the insulated food compartment 2| is a machinerycompartment 30 containing a refrigerant liquefying means including acompressor 3| driven by the electric motor 68 for compressing therefrigerant and for forwarding the compressed refrigerant to a condenser32 where the compressed refrigerant is 30 liquefied and collected inareceiver 33. From the receiver 33 the liquid refrigerant flows to a highside float: type of valve mechanism 34 which-controls the flow of liquidrefrigerant through a supply conduit 35 to a weight type 35 restrictor36 located at the top of the food compartment 2|. This weight typerestrictor 36 maintains a pressure within the conduit 35 and preventsthe evaporation of the liquid refrigerant before it enters the foodcompartment 2|.

After the liquid refrigerant passes throug the restrictor 36 which maybe of the type shown in Fig. 3, the liquid refrigerant passes into' anevaporating means including a serpentine coil portion 31 which issoldered or otherwise suitably 45 fastened in heat exchange relation toa vertical metal plate 38 which is spaced from, but parallel to, therear wall of the food compartment 2|. After passing through theserpentine coil portion 31, the liquid refrigerant is conducted into 50the freezing compartment 22.

Within the freezing compartment 22 is a weight restricting valve 39better shown in Fig. 3, which weight. restricting valve 39 has anentrance 40 where the refrigerant from the serstricting valve 33 leavesthe valve body through.

the refrigerant conduit 45 which connects to the evaporating portion 44.From the evaporating portion 44 the evaporated refrigerant is returnedto the compressor through the return conduit 45.

By the use of this particular system a higher evaporating pressure andtemperature is maintained within the serpentine refrigerant coil portion31 within the food compartment 2| than in the evaporator portion 44 inthe freezing compartment 22. The pressure and temperature differencebetween these two evaporating pertions is preferably suiilcient tomaintain the entire serpentine coil portion 31 at temperatures abovefreezing while the entire freezing evaporator portion is maintained attemperatures considerably below freezing. The evaporating portion 44 isprovided with means for supporting a plurality of ice trays 45 forfreezing ice cubes, desserts, and other comestibles therein. a

In order to control the operation of the refrigerant liquefying meansand to maintain proper temperatures within the freezing compartment 22and the food compartment 2|, I have provided an improved electricalcontrol means including an electrical circuit having a single contactswitch means 5| and a doube contact switch means 52 located in parallelelectrical circuit relation to each other but inseries with Y theelectric motor circuit 53. These switches. shown diagrammatically,preferably are of the snap acting type. The single contact switch means5| is operated by and responsive to a thermostatic bulb 54 which islocated within the freezing compartment 22. The switch 5| is alsoprovided with a manually operable temperature regulating means 55 whichregulates the opening. and closing of the single contact switch 5| andby means of the temperature regulating spring 55 and the temperatureregulating screw 51 provided with a finger manipulator for varying thetension of the spring 56 so as to cause the opening and closing oftheswitch 5| according to diil'erent pressures and temperatures withinthe freezing compartment 22.

The switch 52 is operated by and responsive to the temperature of thethermostatic bulb 50 located within the food compartment 2|. The switch52 is provided with a manually adjustable temperature regulating meansincluding the temperature regulating spring 5| and a temperatureregulating screw 52 provided with a finger manipulator 53 for regulatingthe opening and closing temperatures of the switch 52. .The switch 52 isprovided with two sets of contacts. One set of contacts 54 controls theflow of electric energy through one portion of the electric motorcircuit 53 which is in parallel with the switch 5| and the other set 55controls the'flow of electric energy through the fan motor electriccircuit 55 arranged in parallel with the electric motor which drives thecompressor 3|. Connected in the electric circuitv 56 is an electricmotor driven fan53 which draws warm air from the top of the foodcompartment down through the duct means 10 located upon the left side ofthe food compartment 2| and circulates the air over the surfaces of theserpentine evaporating portion 31 and the plate 33.

By this control means whenever thetemperature within the foodcompartment 22 reaches its high limit for which the switch 5| is set,the switch 5| will close and cause operation of the electric motor 58and the refrigerant liquefying means. If the temperature within the foodcompartment has not reached the high limit for which the switch 52 isset, the switch 52 will remain in the open position and the motor drivenfan 53 will not operate. The refrigerant will circulate through theserpentlnecoil portion 31 but because the motor driven fan is notoperated little heat will be absorbed from the air within the foodcompartment. After passing through the weight restrictor-valve 33 therefrig- ,erant is at a lower pressure and will evaporate the low limitfor which the switch 52 is set to open. The closing of the switch 52will cause the motor driven fan 53 to operate and withdraw warm air fromthe top of the food compartment and circulate it'over the surfaces ofthe serpentine portion 31 and the plate 35 to cool the air within thefood compartment. The electric motor 58 and the refrigerant liquefyingmeans will continue to operate as long as any one of the switches remainclosed. when both of the switches open the refrigerant liquefying meanswill cease operation. This will take place only when the freezingcompartment and the food compartment have reached the low limits forwhich the switches 5| and 52 are set.

The switches 5| and 52 thus operate independently of each other andthereby control the operation of the refrigerant liquefying means tomaintain proper temperatures within the food compartment 2| and thefreezing compartment 22. By the use of the weight restricting valve 39between the two evaporating portions, the serpentine coil 31 ismaintained at evaporating pressures corresponding to temperatures abovefreezing so that no frost will form thereon. This avoids excessivedrying of foodstuffs within the food compartment. Any moisturecondensing thereon will flow down the surfaces of the plate 58 and becollected in drip pan II. By maintaining the evaporating temperature andpressure within the serpentine portion 31 above freezing, thetemperature of the food compartment 2| is positively prevented fromgoing below freezing and freezing foodstuff stored therein. This avoidsthe danger of freezing the foodstuffs common to systems wherein theevaporator is located entirely within the food compartment and which maybe set at extremely low temperatures occasionally to secure quickfreezing. By forcibly circulating the food compartment air over themoist evaporator surfaces.

a relatively high humidity is maintained within the food compartment.

In Fig. 4 I have shown a modified form of my system, partiallydiagrammatic, in which a similar refrigerant liquefying apparatus 35 isprovided which supplies liquid refrigerant to an automatic espansionvalve 5| controlled by pressure on the outlet side. The expansion valve3| controls the flow of liquid refrigerant to a serpentine evaporatingcoil portion 92 which is located outside of but in heat exchangerelation with the sheet metal inner walls 93 of an insulated foodcompartment 94. This food compartment 94 is provided with duct means 95along one of its side walls a and motor driven fan 99 for circulatingair over the portion of the inner wall 93 to which the serpentine coil92 is fastened. From the serpentine coil portion 92 the refrigerant isforwarded to a second expansion valve 91 also controlled by the pressureon its outlet side. The expansion valve 9'! controls the flow ofrefrigerant through the low pressure evaporating portion 98 locatedwithin the freezing compartment 99. The low pressure evaporating portion98 is provided with shelves for supporting the ice trays NH. The liquidrefrigerant evaporates within the serpentine coil portion 92 and the lowpressure portion 99 of the evaporating means and is returned to theliquefying means through a return conduit I02. The operation of therefrigerant liquefying means and the motor driven fan 96 is controlledby an electric circuit I03 which is similar to the control circuit shownin Fig. l and is similarly provided with switches I94 and I05 responsiveto the temperature of the freezing compartment 99 and the foodcompartment 96.

While the form of embodiment of the invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. A refrigerator including a cabinet containing separate freezing andfood compartments, a refrigerating system including an evaporating meanshaving an evaporating portion in heat exchange relation with the foodcompartment and an evaporating portion in heat exchange relation withthe freezing compartment, said evaporating portions being connected inseries, means for creating a forced circulation of the food compartmentair over the evaporating portion disposed therein, a refrigerantliquefying and condensing means for supplying refrigerant to theevaporating portion in heat exchange relation with the food compartmentand for withdrawing refrigerant from the evaporating portion in heatexchange relation with the freezing compartment, means for maintaining ahigher pressure within the evaporating portion in heat exchange relationwith the food compartment than in the evaporating portion in heatexchange relation with the freezing compartment, means for controllingsaid refrigerant liquefying and condensing means, said last named meansincluding means responsive to the temperature within said freezingcompartment and another means responsive to the temperature within saidfood compartment, said temperature responsive means being arranged to beactuated independently of one another to start and/or stop operation ofsaid refrigerant liquefying and condensing means, and one of saidtemperature responsive means being arranged to means for creating aforced circulation of the food compartment air over the evaporatingportion disposed therein, a refrigerant liquefying and condensing meansfor supplying refrigerant to the evaporating portion in heat exchangerelation with the food compartment and for withdrawing refrigerant fromthe evaporating portion in heat exchange relation with the freezingcompartment, means for maintaining a higher pressure within theevaporating portion in heat exchange relation with the food compartmentthan in the evaporating portion in heat exchange relation with thefreezing compartment, means for controlling said refrigerant liquefyingand condensing means, said last named means including means responsiveto the temperature within said freezing compartment and another meansresponsive to the temperature within said food compartment, saidtemperature responsive means being arranged to be actuated independentlyof one another to start and/or stop operation of said refrigerantliquefying and condensing means, and the means responsive to thetemperature of said food compartment being arranged to cause operationof said air circulating means simultaneously with the causing ofoperation of the refrigerant liquefying and condensing means thereby.

3. A refrigerating apparatus including separate compartments to becooled, a closed refrigerant system including a cooling element in heatexchange relation with one of said separate compartments and anothercooling element in heat exchange relation with the other of saidseparate compartments, means for creating a forced circulation of air inone of the said compartments, said closed refrigerant system alsoincluding a refrigerant circulating means for supplying refrigerant tosaid cooling elements, means for controlling said refrigerantcirculatingmeans, said last named means including means responsive to thetemperature within one of said separate compartments and another meansresponsive to the temperature within the other of said separatecompartments, said temperature responsive means being arranged to beactuated independently of one another to start

